JP2009012293A - Printing method and printed object for penetration dry offset printing ink - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a printing method that can realize a wider color domain than a color reproduction domain of RGB expressed by a conventional four color printing process of yellow, red, indigo blue and Indian ink. <P>SOLUTION: The invention refers to a printing method of a penetration dry offset printing ink for printing on a high white newspaper paper with 60-85% of whiteness using two or three inks out of yellow, red, and indigo blue, together with an Indian ink, and by printing with the combination of inks of two inks out of the specific yellow ink, red ink and indigo blue ink together with an Indian ink, and furthermore, with the combination of the specific three color inks together with an Indian ink, the color area of L*a*b* color coordinate system can be expanded. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to a printing method of penetrating dry type offset printing ink comprising a combination of four process colors of yellow, red, indigo and black and an FM screen plate. The ink has four colors and high color reproducibility. The present invention relates to a printing method using the system.

  In addition, on the newspaper paper with high whiteness (high white newspaper), the above-described penetrating dry type offset printing ink comprising four process colors of yellow, red, indigo and black, which can reproduce the high-saturation color, is used. The present invention relates to a printing method for penetrating dry type offset printing ink, which is excellent in color reproduction with high saturation, which cannot be achieved by a conventional penetrating dry type offset printing ink printing method.

  The IT revolution that began in the 1990s has led the environment surrounding the printing site to the direction of digitalization. By this digitization, workflow of conventional printing methods (photographing, positive, scanning, data, design, EPS)・ Imposition, film, printing plate, printing) was a multi-stage process, but it has succeeded in dramatically shortening the process with digital camera shooting, DTP, CTP, and printing. As a result, “RGB” conversion of the submitted data is being standardized, and the current situation is that the data to be handled is shifting to a wider color reproduction region.

  However, in lithographic offset printing consisting of four process colors (CMYK) of yellow, red, indigo and black, which are currently mainstream, the color reproduction area is necessarily narrower than that of RGB because of the hue due to subtractive color mixing. The difference in color reproducibility between digital data and printed matter became a problem.

  In particular, in paper printing (newspaper printing) using penetrating dry ink, there are problems of whiteness and smoothness of paper, and the color reproduction area is narrower than that for coated paper, and sample from digital data. The difference in color reproducibility with the printed matter becomes a serious problem.

  In newspaper printing using penetrating dry ink, there is a growing demand for more colors in recent years, and there is a tendency for color pages on newspapers to increase. Differentiation of the paper surface by quality improvement is strongly desired.

  As means for solving this, in Patent Document 1, a printing method using an ink set of 5 to 7 colors is established as a high-saturation printing system. As a printing method using an ink set having each specified hue, process 4 colors are used. 6 colors (hexachrome printing) with orange and green added to 7 colors and 7 colors (high fidelity printing) with orange, green and purple added to 4 process colors have been established. In addition, as represented by hexachrome ink, as a means of expanding the color reproduction area, a technique such as adding a fluorescent pigment to a part of the color is used. However, deterioration of printability (transfer defect, gloss reduction, etc.) There are also disadvantages such as fading of printed matter due to insufficient light resistance. Furthermore, the number of ink colors used is 6 or 7, and an expensive multicolor printing machine with 6 or more printing cylinders is required. It is an indispensable condition, and it is limited to using this system due to huge capital investment and complicated color management to start a new one.

  Patent Document 2 discloses a printing method using a four-color ink set as a high-saturation printing system, but there is no description of a method for producing each color ink, and there is a great doubt as a patent.

  In newspaper printing, most of the printers are for four-color processes, and multi-color machines with five or more colors have not been introduced to the market as general-purpose products. Therefore, it is more difficult to increase the color saturation of the paper surface by the multicolor printing method. Therefore, it is important to establish a printing method in order to obtain high color rendering ink and to obtain high color saturation including printing paper.

  Conventionally, in newspaper printing, attempts have been made to increase the saturation by increasing the ink volume and increasing the density on the paper surface, but increasing the ink volume increases the saturation of the paper surface. However, the setability is delayed, and the offset dirt and guide dirt are induced. In addition, attempts have been made to increase the pigment concentration and increase the paper surface density without changing the ink volume, but this has led to deterioration of printing suitability such as emulsification suitability. The offset ink printing method is generally not widespread.

  Patent Document 3 discloses the following. That is, amplitude modulation screening (AM screening) that expresses color shading with the size of halftone dots (dots) most commonly used from the contact screen era to the present as a technology related to plate making. The advantages of the AM screen are that it is easy to predict the color tone when printing due to the reproduction of a uniform and beautiful flat net without grainy texture, natural finish, and accumulated experience over many years. . However, at present, the occurrence of interference moiré, rosette patterns, etc. due to the influence of the screen angle is unavoidable. The rosette pattern is solved by increasing the number of screen lines, but changing the number of lines unnecessarily is not suitable for actual printing in consideration of halftone dot collapse. In recent years, with the advance of plate making technology by CTP, frequency modulation screening (FM screening) that arranges finer dots randomly for AM screening and changes the density of the dots to express color shading is increasing. Yes, high-definition (fine) expression has become possible by suppressing the occurrence of moiré and rosette patterns, which is a problem with AM screens, but it is difficult to predict the color tone of the final printed matter, and for printing standardization There were problems such as the necessity of conditioned conditions.

On the other hand, FM screening is expected to improve the sharpness of the image by reducing the film thickness of the ink and to improve the color reproduction area. However, the combination of the conventional process 4 colors and FM screening makes the ink itself. Since the color reproduction area is limited (the color reproducibility of the solid part is not different from that of AM screening), the improvement was limited. Recently, hybrid type screening combining the advantages of AM screen and FM screen is also increasing (Patent Document 4).
JP 2001-260516 A Special table 2007-500091 gazette JP 7-264402 A JP-A-10-210292

  The present invention has been made in order to solve such problems in the prior art, and the problem is that an RGB color reproduction region using a four-color printing machine that has been widely used in the past. The present invention provides a penetrating dry offset printing ink comprising four process colors of yellow, red, indigo and black, and a printing method thereof.

That is, the present invention is a penetrating drying method in which any two or three of yellow ink, red ink, indigo ink, and black ink are used and printed on high white newsprint with a whiteness of 60 to 85%. In mold offset printing, printing is performed using a plate of a frequency modulation screen (FM screen), and the density values of yellow, red, and indigo are 0.90 to 1.00 for yellow, and 0. When each color ink is printed in the range of 90 to 1.02 and indigo in the range of 0.90 to 1.05 by single or superposition, the chromaticity by the L * a * b * color system (JIS Z 8729) is
Yellow ink, L *: 82 to 92, a *: -10 to 0, b *: 75 to 85
Red ink, L *: 55-65, a *: 56-67, b *: -24 to -12
Indigo ink, L *: 55 to 65, a *: −35 to −25, b *: −50 to −35
The chromaticity of overprinting of the above two ink colors is (JIS Z 8729),
By overprinting red ink and yellow ink,
L *: 52-62, a *: 47-57, b *: 30-40
By overprinting indigo ink x yellow ink,
L *: 50 to 60, a *: −55 to −40, b *: 20 to 30
By overprinting indigo ink x red ink,
L *: 37 to 47, a *: 12 to 27, b *: −47 to −37
Printing method of penetrating dry type offset printing ink excellent in color reproduction with high saturation within the range of the above, comprising the combination of the above three colors, the combination of the above two colors and black ink, and further the above three colors Printing method of penetrating dry offset printing ink that can expand the color space of L * a * b * color system that could not be achieved by conventional printing methods by printing with a combination of ink and black ink It is.

  The present invention also relates to a method for printing the above-mentioned osmotic dry offset printing ink, wherein the dots obtained by frequency modulation screening are 1 to 50 μm.

  By using the printing method of penetrating dry type offset printing ink provided by the present invention, a wider color area than the RGB color reproduction area expressed by the conventional four-color printing of yellow, red, indigo and black ink processes can be obtained. It becomes possible to reproduce. Furthermore, by combining with the FM screen plate, it is possible to express a wider color reproduction area than when printing using the conventional AM screen plate. Further, in the present invention, since a fluorescent pigment is not used as a means for improving the color reproduction region of the printed material, a highly saturated printed material can be obtained without deteriorating printability, fading with time of the printed material, and the like.

  In addition, by using high white newsprint paper, which has a much higher whiteness than the ISO standard Japanese color paper for newspapers, absorption in the visible light region due to additional paper, especially absorption in paper with a wavelength range of 380 to 600 nm. In particular, the reflectance of the yellow, green (indigo x yellow), indigo, blue-purple (indigo x crimson) region is improved, and the color reproducibility of yellow, green, indigo, and bluish purple is greatly improved. It becomes possible.

  Next, the present invention will be described more specifically with reference to preferred embodiments.

The present invention comprises a pigment, a vehicle component obtained by heating and dissolving a synthetic resin, a vegetable oil, and a petroleum solvent together with a gelling agent such as aluminum stearate or aluminum chelate as necessary, and an auxiliary agent such as a friction-resistant agent. A high-white newsprint with a whiteness of 60 to 85%, such as a high-white newsprint manufactured by Oji Paper Co., Ltd. (weighing 52 g / m ² , L *: 92, a *: 0.2, b *: 0.8) using an FM screen plate and printing yellow, red, and indigo in Gretag Macbeth Spectro Eye (45/0, D50, 2 degree field of view) : Status T) Concentration values measured with densitometers are in the range of 0.90 to 1.00 for yellow, 0.90 to 1.02 for red, and 0.90 to 1.05 for indigo. Sometimes the chromaticity (JIS Z 8729) according to the L * a * b * color system of the single color and the overprint of each single color is
Yellow ink, L *: 82 to 92, a *: -10 to 0, b *: 75 to 85
Red ink, L *: 55-65, a *: 56-67, b *: -24 to -12
Indigo ink, L *: 55 to 65, a *: −35 to −25, b *: −50 to −35
The chromaticity of overprinting of the above two ink colors is (JIS Z 8729),
By overprinting red ink and yellow ink,
L *: 52-62, a *: 47-57, b *: 30-40
By overprinting indigo ink x yellow ink,
L *: 50 to 60, a *: −55 to −40, b *: 20 to 30
By overprinting indigo ink x red ink,
L *: 37 to 47, a *: 12 to 27, b *: −47 to −37
It is characterized by being in the range of

  As a method for expressing the color reproduction area, an XYZ color system (CIE1931 color system), an X10Y10Z10 color system (CIE1964 color system), an L * a * b * color system (CIE1976), a Hunter Lab color system, Munsell color system, L * u * v * color system (CIE1976), and the like.

  In the L * a * b * color system, “brightness” is expressed by L * as the degree of brightness that can be compared regardless of hue, and indicates that the color becomes brighter as L * increases and becomes darker as it decreases. . In addition, “hue” that differs depending on each color is indicated by a * and b * values, a * indicates a red (+) to green (−) direction, and b * indicates a yellow (+) to blue (−) direction, In each direction, the color becomes brighter as the absolute value increases, and the color becomes dull as it approaches 0. This makes it possible to digitize one color using L *, a *, and b *. In addition to “lightness” and “hue”, there is “saturation (C)” as a method for digitizing the degree of vividness, which can be obtained by the following calculation formula.

Ｃに関しても同様に、絶対値が大きくなるに従って色鮮やかになり、値が小さくなるにつれてくすんだ色になることを示している。

Similarly, C shows that the color becomes brighter as the absolute value increases, and the color becomes dull as the value decreases.

  All color reproduction areas that can be represented by a single printed matter (including color spaces other than printed matter) are called color rendering regions (gamut). The simplest way to represent gamut is as follows: a * is the horizontal axis, b * vertical axis In the two-dimensional space, the solid color part (yellow, red, indigo) and the solid color overprinting part (yellow x red, red x indigo, indigo x yellow) total of 6 colors a * vs b *, It can be expressed by the plotted hexagonal area. The larger the gamut area, the wider the color reproduction area.

  The high white newsprint used in the present invention is preferably a high white newsprint with a whiteness of 60 to 85%, more preferably 63 to 85%. If it is 60% or less, the whiteness of the paper that is currently used generally is about 53%, so a large difference cannot be obtained, and if it is 85% or more, the whiteness is increased. This makes it impossible to maintain the ratio of old waste paper, which increases the cost of printing paper and further imposes a burden on the environment. The high white newsprint used in the present invention may be acid paper or neutral paper as long as the whiteness is in the range of 60 to 85%.

  Generally, in the case of printing with a penetrating dry ink (especially for newspaper printing), about 5 to 15% of the absorption of paper is potentially caused over a portion of the visible light region of 380 to 600 nm. ing. As a result, the reflectance in this wavelength region decreases and the yellowish hue of the paper becomes stronger, so the effect of coloration of the blue component by the copper halide phthalocyanine compound, particularly from the purple region of the indigo and red layer, to the indigo and yellow colors. The coloring effect is hindered over the overlapping green region. However, by printing on high-white newsprint with high whiteness, it becomes possible to increase the reflectance in the visible light region from 380 to 600 nm by 5 to 15%, so the color reproduction region of indigo ink is reduced. In addition, the green and purple color reproduction areas overprinted with yellow and red inks can be expanded more than when using a conventional reprint paper. Since the effect of improving the reflectance in the visible light region of 380 to 600 nm becomes higher as the paper with higher whiteness is printed, it is preferable to use high white paper with higher whiteness.

  The yellow pigment used in the present invention is a disazo yellow compound such as CI Pigment Yellow 12, CI Pigment Yellow 13, and the like on a black ink printed within a density value range of 1.10 to 1.20. In addition, if the L * value when the density of the yellow ink is overprinted in the range of 0.85 to 0.91 has transparency not exceeding 31, the smoothness used for newspaper printing is inferior, In the case of a paper with poor whiteness, the original color developability of the yellow ink is obtained by concealing the lower paper, so that a good color reproduction region can be obtained. If the L * value is less than 31, the original color developability of yellow ink cannot be obtained due to the influence of the lower paper.

  Further, it is also possible to use C.I. Pigment Yellow 83 as a complementary color by adding 0.5 to 10%, preferably 2 to 5% of the above yellow pigment.

  Examples of red pigments include, but are not limited to, rhodamine-based dyes such as rhodamine B, rhodamine 3G, rhodamine 6G, molybdenum, tungsten metal lake compounds such as C.I. Pigment Red 81 and C.I. Pigment Violet 1. These red pigments may be used alone or in combination of two or more. These red pigments should be contained in an amount of 10 to 30%, more preferably 10 to 20%, based on the total ink.

  Examples of indigo pigments include phthalocyanine compounds such as C.I. Pigment Blue 15: 3 and C.I. Pigment Blue 15: 4. Further, C.I. Pigment Green 7 may be used as a complementary color by adding 5 to 15%, preferably 8 to 11% of the indigo pigment.

  The copper phthalocyanine compound, which is a cyan pigment used in the present invention, is a substance exhibiting a crystal polymorphism (homogeneous heterocrystal), and α, β, γ, ε, π, τ, ρ, χ depending on the crystal structure. However, it is preferable to use a β-type having excellent crystal stability and dispersibility, and more preferably a fine β-type copper phthalocyanine having a specific surface area of 74 m 2 / g or more. .

  Examples of the black pigment include carbon black such as C.I. Pigment Black 7.

  As the synthetic resin used in the present invention, rosin-modified phenol resin, petroleum resin, alkyd resin, rosin-modified alkyd resin, petroleum resin-modified alkyd resin, rosin ester and the like can be considered. Preferably, a rosin modified phenolic resin is used. The rosin-modified phenol resin is not particularly limited, but it is preferable to use a resin having a weight average molecular weight of 10,000 to 300,000. When the molecular weight is 10,000 or less, the viscoelasticity of the ink is lowered, and when it is 400,000 or more, the fluidity as the ink becomes insufficient.

  Examples of vegetable oils include those derived from vegetable oils such as palm kernel oil, palm oil, cottonseed oil, peanut oil, palm oil, corn oil, olive oil, linseed oil, corn oil, soybean oil, safflower oil, and tung oil, Those thermal polymerized oils and oxygen-blown polymerized oils can also be used. Moreover, in this invention, these vegetable oils may be used independently and can also be used in combination of 2 or more type.

  The petroleum solvent used in the ink has an aromatic hydrocarbon content of 1% or less, an aniline point of 75 to 95 ° C, preferably 80 to 95 ° C, and a boiling point of 260 to 350 ° C, preferably 280 to 350. It is a petroleum solvent in the range of ° C. If the aniline point is less than 75%, the ability to dissolve the resin is too high, which is not preferable because the ink setting property is slow, and if it exceeds 95 ° C., the resin solubility is poor, so Meat etc. are bad and not preferable. When the boiling point is less than 260 ° C., the evaporation of the ink solvent on the printing press increases, and the transferability of the ink to a roller, a blanket, a plate, or the like deteriorates due to the deterioration of the fluidity of the ink. On the other hand, when the temperature exceeds 350 ° C., the evaporation of the solvent that has penetrated into the paper is slowed down, resulting in deterioration of the penetration property.

  Furthermore, the offset ink composition of the present invention includes a gelling agent, a pigment dispersant, a metal dryer, a drying inhibitor, an antioxidant, an antifriction agent, an anti-set-off agent, and a nonionic surface active as required. Additives such as agents and polyhydric alcohols can be used as appropriate.

  FM screening used in the present invention may also be referred to as random screening or stochastic screening. The FM screening referred to in the present invention refers to a method of expressing the color density by modulating the interval between dots, that is, periodicity, and the frequency (dot density) of hitting basic dots. Specifically, crystal raster screening method, diamond screen method, class screening method, full tone screening method, velvet screening method, accutone screening method, megadot screening method, clear screening method, monet screening Laws are known. All of these methods have different dot generation algorithms, but are methods of expressing shading by changes in dot density, and are FM screening methods.

  In addition, the AM screening method is a method of expressing gradation by the size (halftone dot area) of regularly arranged halftone dots. Depending on the shape of the halftone dot, a square dot screen, a chain dot screen, etc. It is used as various screening methods. In the AM screening method, the number of screen lines (the number of halftone dots arranged per inch) is used as a method of expressing the resolution, and AM at any resolution of high-definition line printing of about 65 to 1500 lines. A screening method can be used. Since the arrangement of halftone dots by AM screening is regular, moire tends to occur when a plurality of halftone dots are overlapped. In a normal four-color print, the color document is separated into four colors (C and M). , Y, K), the occurrence of moire was prevented by shifting the angle of the mesh screen for each color. In general, there are some screens that divide the mesh screen angle from 0 to 90 degrees, but even if the moire can be made difficult to recognize, the moire is completely prevented as long as the regular halftone dot is used. I can't do it.

  A dot having a certain size used in the FM screening method is preferably a dot of 1 to 50 μm. If it is 1 μm or less, although depending on the printing method, it is difficult to reproduce a stable dot diameter, the density gradation that is expressed becomes unstable, and if it exceeds 50 μm, the practical performance of the resolution is inferior. In general, considering printing suitability, 10 to 20 μm is preferable.

  The FM screening method is also a kind of area gradation, which is the same as the conventional halftone dot, but the biggest feature is that there is no regularity, and the moire caused by the regularity and also the generation of rosette patterns There is an advantage that can be eliminated.

  On the other hand, in FM screening, since dots are randomly arranged, it is also true that roughness occurs in the flat net, particularly in the intermediate flat net. This is because there are simultaneous “locations where” adjacent dots and “locations where they do not contact”, which are recognized as rough.

  As a means for solving the above problems, development of hybrid screening that combines both the ease of handling of AM screening and the high quality of FM screening has been progressing recently. Hybrid screening is to use different screens according to the shade of the image and to perform optimal expression in every part of the pattern. FM screening is performed in the highlight area (1-10%) and shadow area (90-99%). This is a method of expressing gradation by changing the size of halftone dots in the intermediate region of 10 to 90% by changing the halftone dot density as in AM screening. In recent years, with the introduction of CTP, high value-added printing using such new screening has been increasing.

  In the present invention, by using an ink having a wider color reproduction area than the Japan color compliant ink used for general offset printing, the ink itself has a wider color reproduction area and is further printed in combination with an FM screen plate. By doing so, it is effective in expanding the color reproduction area. This is because the ink film thickness in the light to middle part is reduced compared to the AM screen, so that the transparency of the ink is increased, the vividness of the image is increased, and the color reproducibility is excellent.

EXAMPLES Next, although an Example demonstrates this invention further in detail, the scope of the present invention is not limited to these description Example. In addition, the part of the following description represents a weight part and% represents weight%.
(Production of rosin-modified phenolic resin gel varnish A for offset)
38.5 parts of rosin modified phenolic resin (Arakawa Chemical Industries, Ltd .: weight average molecular weight 150,000, acid value 20, softening point 160 ° C.) in a four-necked flask equipped with a condenser, thermometer and stirrer, soybean oil 30 parts, 30 parts of AF Solvent No. 5 (manufactured by Nippon Oil Co., Ltd.) were charged, heated to 180 ° C., stirred at the same temperature for 30 minutes, allowed to cool, and ethyl acetoacetate aluminum as a gelling agent 1.0 part of diisopropoxide (ALCH manufactured by Kawaken Fine Chemical Co., Ltd.) was added and stirred at 180 ° C. for 30 minutes to obtain a rosin-modified phenol resin gel varnish A for offset (hereinafter referred to as gel varnish A).

[Ink Example] (Yellow ink)
In the formulation shown in Table 1, C.I. I. Pigment Yellow 12 (LIONOL YELLOW 1245-P manufactured by Toyo Ink Manufacturing Co., Ltd.) was subjected to primary dehydration by gradually adding and kneading Gel Varnish A in a kneader at a temperature of 75 ° C. Next, vacuum dehydration was performed for 1 hour under conditions of a kneader temperature of 100 ° C. to 120 ° C. and a degree of vacuum of 76 mmHg, and secondary dehydration was performed so that the water content in the base ink was 0.5% or less. After dehydration, the remaining gel varnish A, AF solvent No. 5 and soybean oil were added, kneaded and diluted, and the undispersed base ink was taken out from the kneader. The extracted base ink was kneaded using a three roll with a roll temperature of 60 ° C. with a dispersed particle measuring machine (grind meter) to 7.5 μm or less to obtain yellow base ink 1. Next, gel ink varnish A, soybean oil, compound and AF solvent No. 5 were added to the base ink 1 according to the formulation shown in Table 2 to obtain yellow ink 1.

[Ink Example] (Red ink)
As with the yellow ink, C.I. I. A red base ink 2 was obtained using Pigment Red 81 (Funal Rose RNN-P manufactured by Fuji Kasei Co., Ltd.). Subsequently, the gel ink varnish A, soybean oil, the compound, and AF solvent No. 5 were added to the base ink 2 according to the formulation shown in Table 2 to obtain a red ink 2.

[Ink Example] (Indigo ink)
In the formulation of Table 2, C.I. I. Pigment Blue 15: 3 (LIONOL BLUE FG 7330 manufactured by Toyo Ink Mfg. Co., Ltd.) was mixed with varnish, and after milling with a dispersion particle measuring machine (grind meter) to 7.5 microns or less, soybean oil, Compound and AF Solvent No. 5 were added to obtain indigo ink 3. The transparency of yellow ink was evaluated by the following test method.

  Overprinted with black ink density in the range of 0.80 to 1.10 on the black ink printed on the newspaper reprint surface within the density value range of 1.10 to 1.20, and measured the L * value. did. The results are shown in Table 4.

  The yellow ink of the example does not exceed L * even when the density value is increased to 1.10, and does not affect the black ink of the underprint, and is excellent in transparency (L * has a small value) Indicating that it is blacker and whiter as it gets larger).

  On the other hand, L * is high in the comparative example, and it can be seen that the black ink of the underprinted ink is hindered because the yellow ink of the overprinted is opaque.

[Printing evaluation test]
About the ink of the said Example and a comparative example, under the following printing conditions, each solid density value of yellow, red, and indigo is yellow: 0.90-1.00, red: 0.90-1.02, indigo: Printing was performed within the range of 0.90 to 1.05, and the printed matter was evaluated. The ink used was a general offset newspaper printing ink, and was printed within a density range of 1.12 to 1.20.

[Printing conditions]
The FM screen used was Staccato manufactured by Kodak Corporation, and the AM screen used 100 lines. The printing paper is Koshiro Newspaper (Oji Paper Co., Ltd.) (medium quality paper: weighing 52 g / m ² , colorimetric values: L *: 92, a *: 0.2, b *: 0.8), Japan Table 3 using newspapers manufactured by Paper Industries Co., Ltd. (ultralight paper: weighing 43 g / m ² , colorimetric values: L *: 82, a *: −0.4, b *: 4.6) A print test was conducted with a combination of

The detailed conditions regarding printing are shown below.
Printing machine: LITHOPIA BT2-800 NEO (Mitsubishi Heavy Industries, Ltd.)
: Printing order: Ink → Indigo → Red → Yellow Dampening water: NEWSKING ALKY (Toyo Ink Manufacturing Co., Ltd.) 0.5% tap water solution Printing speed: 100,000 parts / hour Dry offset printing ink was used.

[Printing condition]
Density: Measure the density value of the solid part (yellow, red, indigo, black) of the printed matter with Gretag Macbeth Spectro Eye (45/0, D50, 2 degree field of view: Status T).
Color measurement: Gretag Macbeth Spectro Eye (45/0, D50, 2 degree field of view: Status T) Single color solid part (yellow, red, indigo) of printed matter and single color solid overprinted part (yellow x red, red) × L *, a *, b * values of indigo, indigo × yellow).
The C value was determined from the following formula using a * and b *.

結果を表４、５に示す。比較例と比べて実施例のＣ値が大きく、印刷物の彩度が高い。また、ａ*を横軸、ｂ*縦軸とした2次元空間に、各ａ*、ｂ*値をプロットし、２次元のガモットで比較した結果、実施例の色再現領域が広いことがわかる。

The results are shown in Tables 4 and 5. Compared to the comparative example, the C value of the example is large, and the chroma of the printed matter is high. In addition, as a result of plotting each a * and b * value in a two-dimensional space with a * as the horizontal axis and b * vertical axis and comparing them with a two-dimensional gamut, it can be seen that the color reproduction region of the embodiment is wide. .

Claims (3)

In osmotic dry offset printing that uses any two or three of yellow ink, red ink, and indigo ink, and black ink to print on high white newsprint with a whiteness of 60 to 85%, Printing is performed using a plate of a frequency modulation screen (FM screen), and the density values of yellow ink, red ink, and indigo ink are 0.90 to 1.00 for yellow ink and 0.00 for red ink. Chromaticity (JIS Z 8729) by L * a * b * color system when each color ink is printed by single or superposition within the range of 90 to 1.02, indigo ink 0.90 to 1.05 ,
Yellow ink, L *: 82 to 92, a *: -10 to 0, b *: 75 to 85
Red ink, L *: 55-65, a *: 56-67, b *: -24 to -12
Indigo ink, L *: 55 to 65, a *: −35 to −25, b *: −50 to −35
The chromaticity of overprinting of the above two ink colors is (JIS Z 8729),
By overprinting red ink and yellow ink,
L *: 52-62, a *: 47-57, b *: 30-40
By overprinting indigo ink x yellow ink,
L *: 50 to 60, a *: −55 to −40, b *: 20 to 30
By overprinting indigo ink x red ink,
L *: 37 to 47, a *: 12 to 27, b *: −47 to −37
Printing method of penetrating dry type offset printing ink excellent in color reproduction with high saturation within the range of the above, comprising the combination of the above three colors, the combination of the above two colors and black ink, and further the above three colors Printing method of penetrating dry offset printing ink that can widen the color space of L * a * b * color system by printing with a combination of ink and black ink.   2. The printing method for penetrating dry offset printing ink according to claim 1, wherein the dots obtained by the frequency modulation screening method are 1 to 50 [mu] m. A printed matter obtained by printing on a plate of high-white newsprint, printing density, frequency modulation screen (FM screen) according to claim 1.